As disclosed in Japanese Patent Application Laid-open No. 80448/1974 and as shown in FIGS. 1 to 5 of the accompanying drawings as an embodiment, in a conventional roller bearing for providing a rectilinear movement, both a table 2' and a bed 1' are made of steel and are thick, so that the overall bearing structure is heavy and is time-consuming and expensive to manufacture due mainly to the cutting work necessary. Therefore, the number of processing steps is large and the manufacturing cost is high and this manufacturing method is not fitted for mass production. However, high accuracy can be maintained for a long time.
On the other hand, in the U.S. Pat. No. 2,889,181 as shown in FIG. 5A, a thick metal is used as the track member to make the bearing sufficiently rigid, and the track surface is further subjected to heat treatment and grinding in order to obtain high accuracy. Therefore, although the rolling bearing is expensive and heavy and is not fitted for mass production, high accuracy can be maintained for a long time.
However, such a rolling bearing for providing rectilinear movement is not fitted for use in the field where a light load is applied to such a bearing and where it is used in a small limited space. Therefore, there is a large demand for a miniaturized roll g bearing for rectilinear movement.
On the other hand, in U.S. Pat. No. 4,095,854 shown in FIG. 5B, a light-weight ball bearing which is suitable for mass production is disclosed. This bearing is used at, for example, the drawer portion or the like of an office cabinet. The track member is formed into a predetermined shape by being press formed and the track surface is also press formed to reduce the cost of the bearing. Therefore, this bearing is light-weight and suited for mass production and can be manufactured inexpensively. However, there are drawbacks in that the track member lacks rigidity, the hardness and accuracy, etc. of the track surfaces are insufficient, and high bearing accuracy cannot be maintained for a long time. Also, the applicable range is limited since it is used only in the field where the weight of a load which is applied to the bearing is small and a high accuracy is not required.